US829135A - Motor-control system. - Google Patents

Description

PATENTED AUG. 21, 1906.

C. E. BENNETT. MOTOR CONTROL SYSTEM. APPLIUATION FILED DBO.Z8,1905.

To LLER 51 van to r 35:1 h all-11mm UNITED STA ES PATENT oEEIoE.

CHARLES E. BENNETT, OF NEW YORK, N. Y., ASSIGNOR ONEHALF TO ROSENBAUM & STOUKBRIDGE, OF NEW YORK, N. Y., A FIRM. h

MOTOR-CONTROL SYSTEM.

Specification ,of Letters Patent.

Patented Aug. 21, 1906.

Application filed December 28,1906. Serial No. 298,607.

To all whom, it may concern:

Be it known that I, CHARLES E. BENNETT, a citizen of the United States, residin at the city of New York, in the borough of anhattan and State of New York, have invented certain new and useful Improvements in Motor-Control Systems, of which the following/{is a full, clear, and exact description.

y invention relates to a system for-controlhng electric motors, and has particular reference to use with street-cars and similar iatistlallations where heavy currents are han- Trolley-cars are constantly being made larger and heavier and are called upon to run at greater speeds, so that the method of handling the necessary heavy currents upon the street-car platform is dangerous and accidents fre uently occur. For heavy trains the difficu ty is overcome by the multipleunit system in which only an operating-cirfiuit is handled on the car-platform, the

ea neat the cars,where there is plenty of room and where the unavoidable arcing can be so provided for as not to be disastrous. This serves to render the train control entirely safe; but it is evident that the expensive multiple unit system cannot be practically applied to simple street-cars, the complexity and expense being quite prohibitive.

By the present invention I aim to secure all t e advantages of a multiple-unit system in which the heavy specially-constructed contactors beneath the car-platform and at the same time retain practically all the present valuable feat res of the platform-controller now used, with its attendant cheapness and simplicity.

A further object of the invention is to secure an autorhatically-operating magnetic cut-out which is also automatically restored to its normal condition by the return of the controller-arm.

With these' and other objects in view my nvention consists in the construction, combination, location, and arrangement of parts, as hereinafter set forth and shown and finally particularly pointed out in the appended claims.

The drawing illustrates the system of street-car control embodying the principles of my invention.

In order that my invention may be fully currents being controlled wholly be burned up.

currents are broken at.

understood, it is necessary to consider the action of a controller when used to re ulate a motor-circuit. The ordinary control or comprises a revoluble shaft with cop per segments which contact with fingers, so as to cut out successive resistances Within the armature-circuit. In shutting off the controller the resistances are again successively cut into the circuit until the latter is finally broken as the controller-arm passes from the first not'ch to the off position. As long as the circuit continues there is no great danger of excessive sparking, because a path is always provided for the inductive extra current of the motors; but when the arm leaves the first notch and opens the motor-circuits entirely the inductive current has no path open to it and rises to an uncertain otential, which may be enormously high if t e break is made abruptly. All the practical danger therefore occurs at the first notch of the controller at which the motor acts as a gigantic sparkcoil; but in practice the difficulties from arcing at this notch are very. great and are the cause of a great many controllers bein In carrying out my invention make use of a device which takes the place of the ordinary circuit-breaker on the trolleycar and in addition to this function serves as a contactor for the first notch of the controller. The remainin notches do not need contactors, but will tal re care of themselves for the reason above stated. L

Referring now to the drawing, in which like parts are designated by the same reference-sign 1 indicates the motor-circuit of a trolley-car receiving current from the usual trolley-conductor 2, pole 3, and wire 4. At this point are interposed special devices embodying the principles of my invention and which will be later described. This motorcircuit is continued at 5 to the usual controller and motor by connections. (Not shown.)

6 designates the controller of usual or any desired form, having the operatin shaft 7 therein with the usual segments, 0 which 8 designates the first and the one through which the circuit is finally broken when the controller is shut off.

9 designates the usual contact-finger spring pressed from the frame, so as to engage the segment 8 in any desired way. I make the finger 9 and the segment 8 or preferably special contacts 9 8 within the controller and adapted to operate simultane- ,ously therewith part of a shunt or pilot cirl4 and 17 are wound with a large number of turns of fine wire, so that the pilot-current in the wire 10 is merely a light operating-current. It is evident that this circuit remains open for the off osition of the controllerarm, I but that wlienever the controller is moved to the first notch the circuit is completed and the ma net 14 energized. As a result of the comp etion of this pilot-circuit and the energization of the ma net 14 the following actions take place: T e magnetcoil 14 is energized and attracts its armature 19, so that the brushes 20 close a circuit between points 21 and 22, and establish a connection for the motor-current which 11 to this time has been broken at this point. his motor-current then asses into the controller in the usual way. he motor is therefore 0 crating at its proper s eed, depending on tl ie position of the control er-arm. In the meantime the magnet 17 is not energized, so that its armature 23 remains in the position shown. The main motor-circuit 1 has a few turns 24 around this magnet, which I term the supplemental magnet, and these serve to exert a certain amount of attraction on the armature 23, but not sufficient to draw it upward.

Conditions remain as above described during the normal operation of the car, unless for some reason an abnormally heavy current passes through the motor-circuit. Should this occur, the effect of the turns 24 becomes enough strengthened to pull upward the ar mature 23, and bridge the brush 25 across the contact 18, above mentioned, and a' ground connection 26, and thus completes the shunt-clrcmt 16 throu h the magnet-windingr17, above mentionefi.

he effect of completing the circuit, 16'

through the coil 17 is to divert almost all of the shunt or pilot current through the magnet 17 and away from the coil 14 of the circuit-breaking magnet which becomes so much deener 'zed as to release its armature 19 and brea the main motor-circuit at points 21 and 22, This is the desired result,

since it is customary to break the motor-circuit at a circuit-breaker when the current becomes excessive for any reason. The brush 25, however, continues to short-circuit the contacts 18 and 26 on account of the magnetizing effect of the coil 17, which serves the dual lplurpose of short-circuiti the circuit-brea 'ng magnet 14 and provlding the magnetism for holding the armature 23 raised in spite of the breaking of the main motor-circuit. The main motor-circuit is therefore kept broken until the controllerarm is again moved to its off position, whereupon the shunt or pilot circuit 10 is broken at this point, so that everything falls to the normal position.

The above apparatus takes care of all conditions which arise in practice and in addition virtually serves as a cont-actor for the first notch of the controller. The latter effect is secured, since the circuit-breaker alwa s operates when the controller passes off of t e first notch by breakin the circuit through the magnet 14. The eavy arcing due to the extra current is therefore borne by the circuit-breakin magnet, which may have s ecial carbonrushes 27 for this purpose.

an arc should occur at an later segment, the motorman is always able to destroy it promptly b moving his controller to off position, w ich automatically throws the circuit-breaker, as above. The circuitbreaker is always also automatically operated in case of an abnormally hea current. Thus I provide for all conditions w ich arise in practice and secure the control of a trolleycar or any other machinery by a simple system.

What I claim is- 1. In a controller system, a circuit-breaking magnet located in a separate circuit between the potential sources or terminals, means whereby said circuit is broken whenever the controller-arm is moved to 'zero or cuitin relation.

2. a controller system, aciIcuitPbreaking magnet located in a separate circuit between the potential sources or terminals, means whereby said circuit, is broken whenever thecontroller-arm is moved to zero or.

off position, a supplemental compoundwo d magnet arranged to short-circuit said circuit-breaking magnet whenever the current through the motors exceeds a predetermined value, and means whereby said supplemental magnet continues in its attracted relation after an actuation until the con.- troller-arm-is movedto zero or off position.

3. In a controller system, a circult-breaking ma et entirely se arate from the usual contro er and adapts to be located at any convenient point as for example beneath the floor of the car and connections entirely electrical and. including a supplemental mag net for actuatingsaid .circult-breaking magnet whenever the controller is moved to zero or off position, and whenever the current in the motors exceeds a predetermined value, said supplemental magnet having a shuntcoil for holding the circuit-breaking magnet in actuated relation.

4. In a controller system, a circuit-breaking ma net included in a separate circuit across t e potential sources, a supplemental magnet having a winding in series with the motors, and arranged to short-circuit said circuit-breaking magnet in case of excessive current in the motors, and a shunt-winding on said supplemental magnet for maintaining it in attracting relation after each actuation until the controller-arm is moved to zero or off position.

5. In a controller system, a circuit-break: ing magnet entirely separate from the usual control er, a supplemental magnet having a shunt-winding across the winding of said circuit-breakin magnet, said shunt-winding bein norma 1y open circuited, and a series win ing on said supplemental magnet for closing said shunt-winding in case of excessive current in the motor-circuit, and means for breaking all of the said circuits whenever the controller is moved to zero or off position.

In witness whereof I subscribe my signature in the presence of two witnesses.

CHARLES E. BENNETT.

Witnesses:

ALFRED W. PRoo'roR, WALDO M. CHAPIN.

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